Electron discharge device



March 22, 1949. c. A. SCHLElMANN-JENSEN ETAL 2,465,041

ELECTRON DISCHARGE DEVICE Filed Jan. 15, 1945 Patented Mar. 22 1949UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE Sweden,

assignors to Aktiebolaget Svenska Elektronriir, Stockholm, Sweden, acompany of Sweden Application January 15, 1945, Serial No. 572,850 InSweden December 12, 1942 2 Claims. (Cl. 25027 .5)

in which fluorescence produced by electron bombardment is employed forindicating varying voltages, by varying configurations of contrastedluminous and dark areas.

Such electronic voltage indicators as they may be termed have many uses,for example, to indicate the resonant or tuning positions of radioreceivers, in test equipments and modulationmeters etc. Usually, inaddition to a thermionic cathode and a fluorescent anode, they have agrid or other deflecting electrode, which operates at a positivepotential varying with the automatic volume control voltage and thuswith the strength of the input signals.

As a consequence of this fact a greater part of the fluorescent coatingwill be bombarded by electrons from the cathode at high signal voltagesthan at low signal voltages. Now, it is well known that most of thefluorescent materials generally used will fatigue with time ofoperation, that is the brightness of the bombarded sector or sectors ofthe fluorescent screen will diminish at a certain rate according to thetime during which this part of the screen has been bombarded. In radioreceivers which usually are tuned to a local transmitter station thismeans that after a relatively short time of use the greater part of theuseful fluorescent screen will be fatigued and in this way make itdifficult to indicate the exact tuning to a station with lower signalvoltage because in this case the small bombarded section of the screenis positioned entirely within the sector or sectors of the screen whichalready are fatigued from the bombardment by the high signal voltage ofthe local station.

To eliminate this disadvantageous feature it has been proposed insteadof applying the above mentioned positive potential on the deflectingelectrode to operate the tube with a negative potential varyingaccording to the automatic volume control voltage on the deflectingelectrode. However, this method of operation almost always necessitatesthe use of an additional amplifying stage, which of course is veryundesirable.

The main object of the present invention is to achieve an improvement intuning indicators provided with a fluorescent anode and a cathode fromwhich the electron stream is concentrated into one or more beams byusing two control electrodes, disposed between the anode and the cathodeon opposite sides of each electron beam and deflecting the electrons ofthe beam in one and the same direction.

Another object of this invention is to provide an electric dischargedevice comprising within an envelope an indicator section as describedand an amplifier section comprising a grid and an anode, in which thecathode may be common to both sections.

A further object of this invention is to provide an indicatorconstruction in which the two control electrodes together with anauxiliary electrode form an electron-optical lens system for thedeflection of the beam.

A still further object of this invention is to provide an indicator, thesensitivity of which is variable along the fluorescent screen byarranging or shaping, or by both arranging and shaping, at least one ofthe control electrodes asymmetrically in relation to the otherelectrodes of the system.

In the following the terms control electrode and auxiliary electrode areused to denote one such electrode aswell as a combination of more suchelectrodes.

The novel features which we believe to be characteristic for ourinvention are set forth in the appended claims; the invention itself,however, both as to its construction and operation will be bestunderstood by reference to the following description taken in connectionwith the accompanying drawings in which we have indicated someembodiments of the invention.

In the drawings:

Figure 1 shows an electron discharge device ac-,

cording to the invention with parts broken away to show details ofconstruction.

Figures 2 and 3 diagrammatically show two forms of electronic voltageindicators according to the invention.

Figures 4 and 5 are cross-sections of two practical embodiments based onthe diagram shown in Figure 2.

Figure 6 is a cross-section of a practical embodiment based on thediagram shown in Figure 3 Figures '1, 9, 11 and 13 are sections of fourdif- 1, and base 8. Supported from the press are a cathode H, a grid 9and anode ll] surrounding the cathode.

According to the invention the indicating section of the tube is mountedin the upper portion of the envelope I. The indicator comprises acathode, an anode having a conical surface presented to said cathode andprovided with a coating which fluoresces when subjected to electronbombardment, and, disposed between the cathode and the anode on oppositesides of the beam of electrons from the cathode, two control electrodesdeflecting the electrons or" the beam in one and the same direction.

As shown in Figure 1 the cathode II is extended into the upper portionof the envelope I with an emitting section for applying electrons in theindicating device. Two control electrodes in the form of cylinders 3 and4 are positioned above each other and around the cathode having anannular opening between themselves through which electrons pass from thecathode If to the coated anode 2 and form a luminous ring thereon. Onecontrol electrode 4 of the indicator is supported from a bar 5electrically connected to the grid 9 of the amplifier portion of thetube, the other control electrode 3 being supported from a bar 6supporting the anode IU of the amplifier portion. In operation thecontrol electrode 4 has a negative potential and the control electrode 3a positive potential in relation to the cathode ii. If the signalsincrease, the potential of the electrode 4 will grow more negative andthat of the electrode 3 will grow more positive, i. e. the saidelectrodes will deflect the electronic stream upwards, as indicated bythe dash-and-dot lines in Figure 2 which diagrammatically shows theindicator portion of the device in Figure 1. When the signal voltage hasa lower value the electrons will follow the dash lines. Consequently, athigh input voltages different parts of the fluorescent screen 2 will bebombarded by electrons than at low input voltages.

Figures 4 and 5 show indicators based on the same principle asillustrated in Figure 2. One control electrode consists of twointerconnected rings l2 and I4 placed above each other and around thecathode I I. Placed in front of the opening formed between the two ringsI2, I4 is an annular deflecting electrode l3 lying on the anode side ofthe electrode l2, H3 in Figure 4 and on the cathode side in Figure 5. Inthese embodiments of our invention two luminous rings will appear on thefluorescent target, said rings receding from each other upwards anddownwards at strong signals and approaching each other at weak signals.This way of indicating has been found to be especially favourable tofacilitate observation.

In the diagram shown in Figure 3 in addition to the two controlelectrodes 3 and 4, disposed on opposite sides of the electron beam, afurther auxiliary deflecting electrode I5 is arranged on one side of thebeam forming together with the control electrodes 3 and 4 anelectron-optical lens system for the beam passing through the openingbetween the electrodes. The auxiliary electrode l5 may be connectedelectrically to the control electrode 3 lying on the same side of thebeam, or it may be connected to the control electrode 4 lying on theopposite side of the beam. The diagram shows the electrodes 3 and i5working at a positive potential and the electrode 4 at a negativepotential in relation to the cathode.

At high signal volage the electrons follow the dash-and-dot lines and atlower input voltage they follow the dash lines.

The indicator shown in Figure 6 is made according to the principle inFigure 3, but with the deflecting electrode inversely positioned. Inthis case the deflecting electrodes 3 and 4 and the auxiliary electrode15 consist of cylindrical rings, surrounding the cathode II, theelectrode 4 being placed above the electrodes 3 and I5, and theelectrode 3 being so arranged within the electrode 15 that its upperedge is situated in the opening between the electrodes 4 and I5 or is onthe same, or approximately the same level as the upper edge of theelectrode I5. In this case the visible indication on the fluorescentscreen will consist of a luminous ring.

In the indicators shown in Figures 7 to 14 the sensitivity of theindicator is made variable along the screen. According to our inventionthis object is achieved by arranging or shaping, or by both arrangingand shaping, at least one of the deflecting electrodes asymmetrically inrelation to the other electrodes of the system. In other respects theseindicators are based on the principle shown in Figure 2.

In the embodiment of our invention shown in Figures 7 and 8 the controlelectrodes consist of two rings l6 and I! placed above each other andaround the cathode ll. One of the deflecting electrodes, H, is cut offobliquely in relation to the other deflecting electrode l6 to enable avariable sensitivity of the device at variable signal strength. Only oneluminous part will appear on the fluorescent screen 2. The boundariesbetween the luminous and the dark parts of the screen are indicated by adash-and-dot line 20 (Figure 8) in the case of a station with greatsignal strength and by a dash line l8 in the case of a station with lowsignal voltage, the luminous part 2i of the screen lying outside theboundary-lines. In the first case the dark part 22 located to the leftin Figure 8 and having the lower sensitivity is utilized according tothe invention for indication while in the second case the dark part isto the right is made use of, said latter part having the greatestsensitivity.

In the indicator shown in Figures 9 and 10 one of the deflectingelectrodes consists of two interconnected rings 23 and 25 placed aboveeach other and around the cathode ll. Between the rings 23, 25 there isformed a circular opening, in front of which an annular deflectingelectrode 24 is arranged. This annular electrode 24 is shapedasymmetrically in relation to the remaining electrodes of the system andproduces together with the other deflecting electrodes 23, 25 an. innerand an outer luminous ring on the screen 2. The dark intermediaryportion of the screen is indicated by the dash-and-dot lines 20 and 20in the case of a station with great signal strength and by the dashlines l8 and I8 in the case of a station with low signal voltage. Atgreat signal strength the left parts of the dash-and-dot boundaries 20,20 is utilized; at low signal strength the right parts of the dash linesl8, 18 are made use of.

In the indicator shown in Figures 11 and .12 the electrode 26 located inthe opening between the deflecting electrodes 23, 25 has annular shapeand is placed inclined in'said opening. The. dark part on the screenwill appear between the. dashand-dot lines 20 and 28 at "full signalstrength and between the dash lines 18 and 18' on tuning to a stationwith low signal voltage. In the first case the left parts of thedash-and-dot lines 20 and 20' serve to indicate the tuning position, inthe second case the right parts of the dash boundaries I8 and I8 areutilized for the same purpose.

In the indicator according to Figures 13 and 14 the electrode placed inthe opening between the electrodes 23, 25 consists of two half rings 21and 28 arranged opposite each other and at mutually difierent levels. Inthis way the sensitivity of the device becomes different in two 180-sectors, the dark part at high signals lying between the dash-and-dotlines 20 and 20' and at low signals lying between the dash lines I8 andI8. In the first case the lower parts of the dashand-dot lines 20 and20' are utilized to indicate, in the second case the upper parts of thedash lines I8 and I8.

The asymmetrical electrodes 24, 26 and 21, 28 respectively (Figures 9 to14) may be more or less displaced in relation to the opening and evendisplaced on one side of the opening in which case one luminous ringonly will be formed on the fluorescent screen.

Figure 15 schematically shows a further form of the electric dischargedevice according to the invention, comprising within the envelope I anindicator section, containing the fluorescent anode 2, the controlelectrodes 3 and 4, the cathode II, and an amplifier section, containingthe common cathode I I, an anode 29, a control grid 33, a screen grid32, and if desired a suppressor grid 3|, the control grid 33 and thescreen grid 32 being connected each to one of the control electrodes 3and 4 of the indicator section. The object of this particulararrangement is to provide a tube containing a separate amplifier sectionintended to be used as an amplifier in the receiving set or otherapparatus in which the indicator section is utilized to show the tuningposition.

Although we have shown and fully described, by way of example, someembodiments of our invention, it will be apparent that many changes maybe made therein without departinng from the intended scope and spirit ofthe invention. For instance, there may be provided more openings for thestream of electrons between the cathode and the fluorescent target inorder to produce other patterns of the luminating spots on thefluorescent screen as may be suitable for the indi- 80 Number cationdesired.

What we claim is:

1. An electron discharge device having in an envelope an indicatorsection, comprising an anode with a fluorescent coating, an elongatedcathode for producing electrons, two closed ringshaped controlelectrodes surrounding and spaced from the cathode for concentrating theelectrons into at least one beam and for deflecting the electrons ineach beam in one and the same direction, and mounted in the saidenvelope, an amplifying section comprising an anode, a cathode, and acontrol electrode, the anode and the control electrode of the amplifyingsection each being electrically connected to one of the controlelectrodes of the indicator section inside said envelope.

2. An electron discharge device having in an envelope an indicatorsection, comprising an anode with a fluorescent coating, an elongatedcathode for producing electrons, two closed ringshaped controlelectrodes surrounding and spaced from the cathode for concentrating theelectrons into at least one beam and for deflecting the electrons ineach beam in one and the same direction, and mounted in the saidenvelope an amplifying section containing an anode, a cathode, a controlgrid, and a screen grid, the control grid and the screen grid of theamplifying section each being electrically connected to one of thecontrol electrodes of the indicator section inside said envelope.

CARL ARNE SCHLEIMANN-JENSEN. NILS ERIK GUSTAV BACKMARK,

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,051,188 Thompson Aug. 18, 19362,098,231 DuMont Nov. 9, 1937 2,108,880 Braden Feb. 22, 1938 2,243,408Anderson et a1 May 27, 1941 2,273,800 Jensen Feb. 17, 1942 2,283,103Stuart, Jr May 12, 1942 2,318,140 Clark May 4, 1943 2,366,320 ElstonJan. 2, 1945 FOREIGN PATENTS Country Date 495,732 Great Britain Nov. 18,1938

